1. Field of the Invention
The present invention relates to an apparatus for making carbon dioxide snow. The present invention also relates to a method for making carbon dioxide snow.
2. Description of the Related Art
In the manufacture of carbon dioxide (CO.sub.2) snow, the use of snow or the like, with multiple nozzles for injecting liquid CO.sub.2 into a snow chamber for increased production, is a well known practice. The expanding CO.sub.2 ejected through the nozzles forms a snow-vapor mixture in the horn. Upon separation of the snow and vapor, the snow can be used as a refrigerant, optionally after further processing steps such as packing the snow into CO.sub.2 ice.
At least two problems exist in the conventional art. The first is a tendency for the snow to stick to the adjacent walls of the horn. This problem is addressed in U.S. Pat. No. 4,111,362. According to this patent, the sticking arises due to the impact of the snow particles on the adjacent walls of the horn. U.S. Pat. No. 4,111,362 therefore proposes directing linear jets of the snow-vapor mixture against one another in a direction generally transverse to the ultimate direction of snow discharge from the horn so that the elastic rebound of the impinging jets dissipates the kinetic energy of the snow particles. The essential feature in that patent is that the angles of intersection of the impinging linear jets are such that the resulting kinetic energy of all the jets is substantially zero and the high velocities and turbulence of the jets are practically eliminated. However, the proper operation of the snow making system of U.S. Pat. No. 4,111,362 depends upon very precise orientation of the nozzles since the failure of the jets to collide at substantially 180 will dramatically reduce energy dissipation.
The second problem is that of retaining the produced snow in a confined area. Conventional CO.sub.2 snow forming equipment discharges the produced snow in a broad pattern and relies upon a receiving container to deflect the CO.sub.2 snow into a desired area. The receiving container must be at least partially open in order to permit removal of the stored snow, and so the receiving container must have a minimum height in order to retain the snow from blowing out of the container.